From the Other Side

In last month's FTOS, I mentioned the commuter rail in the San Francisco area. I said that the odds of my being under the bay if an earthquake hits was about one in 70. Clearly, the odds are greatly affected by the conditions I place or imply by the question. First implication: The “Big One” would hit on a workday. One could have calculated the odds if it hit on a weekend rather than a workday — or if it hit in a given month or year. Seismologists have been trying diligently to determine the odds of when this big earthquake will happen. I also read that the California seismologists were able to give the affected citizenry notice of an earthquake. But in actuality, the timing for the warning was the time difference between the arrival of the P-wave and the following destructive surface waves. I don't recall how long that was. It depended on how far away you were from the epicenter.